Summary of Urban Effects on Clouds and Rain

BrahamJr., Roscoe R.; Semonin, Richard G.; Auer, August H.; ChangnonJr., Stanley A.; Hales, J.M.

doi:10.1007/978-1-935704-29-4_7

Cited by 29 publications

(24 citation statements)

References 7 publications

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“…In METROMEX "airmass" storms were found to occur 116% more frequently downwind of St. Louis than in rural areas (Changnon et al 1981). Huff and Vogel (1978) found that 43% of the storms affecting the St. Louis area came from the southwest and westsouthwest during METROMEX.…”

Section: Case Studymentioning

confidence: 99%

“…Results from METROMEX indicated that summer precipitation was typically enhanced by 5%-25% over background values within 50-75 km downwind of the urban region (Huff and Vogel 1978;Changnon 1979;Braham et al 1981, Changnon et al 1981, 1991. More recent observations in several cities show an increasing thunderstorm frequency associated with increased population growth within these cities (Balling and Brazel 1987;Jaurequi and Romales 1996).…”

Section: Introductionmentioning

confidence: 99%

“…Observations from field campaigns like the Metropolitan Meteorological Experiment (METROMEX) (Braham 1976;Changnon et al 1981) conducted over St. Louis, Missouri, suggest that large urban regions can influence precipitation and convection occurring over and downwind of such regions. Results from METROMEX indicated that summer precipitation was typically enhanced by 5%-25% over background values within 50-75 km downwind of the urban region (Huff and Vogel 1978;Changnon 1979;Braham et al 1981, Changnon et al 1981, 1991.…”

Section: Introductionmentioning

confidence: 99%

“…These include one or a combination of the following: 1) greater aerosol concentrations within urban regions act as cloud condensation nuclei (CCN), giant CCN (GCCN), and ice nuclei (IN) (e.g., Gunn and Phillips 1957;Squires 1958;Squires and Twomey 1961;Warner and Twomey 1967;Warner 1968;Rosenfeld 1999Rosenfeld , 2000Borys et al 2000Borys et al , 2003Ramanathan et al 2001;Diem and Brown 2003;Andreae et al 2004;Givati and Rosenfeld 2004;Molders and Olson 2004;Jirak and Cotton 2006); 2) increased surface roughness of urban areas leads to enhanced surface convergence over and downwind of the urban region (e.g., Hjelmfelt 1982;Bornstein and Lin 2000;Craig and Bornstein 2002;Rozoff et al 2003); 3) the urban canopy diverts thunderstorms around urban regions (e.g., Loose and Bornstein 1977;Bornstein and Lin 2000); 4) the urban region serves as an enhanced source of moisture (e.g., Dixon and Mote 2003); and 5) sensible and latent heat fluxes within the urban region and thermal perturbations of boundary layer by the urban heat island (UHI) affect moist and dry convection (e.g., Braham et al 1981;Changnon et al 1981;Thielen et al 2000;Baik and Kim 2001;Shepherd et al 2002;Shepherd and Burian 2003;Rozoff et al 2003). These effects are discussed in an excellent recent review article by Shepherd (2005) to which the reader is referred for further details.…”

Section: Introductionmentioning

confidence: 99%

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Urban Aerosol Impacts on Downwind Convective Storms

Heever

Cotton

2007

Journal of Applied Meteorology and Climatology

289

140

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The impacts of urban-enhanced aerosol concentrations on convective storm development and precipitation over and downwind of St. Louis, Missouri, are investigated. This is achieved through the use of a cloud-resolving mesoscale model, in which sophisticated land use processes and aerosol microphysics are both incorporated. The results indicate that urban-forced convergence downwind of the city, rather than the presence of greater aerosol concentrations, determines whether storms actually develop in the downwind region. Once convection is initiated, urban-enhanced aerosols can exert a significant effect on the dynamics, microphysics, and precipitation produced by these storms. The model results indicate, however, that the response to urban-enhanced aerosol depends on the background concentrations of aerosols; a weaker response occurs with increasing background aerosol concentrations. The effects of aerosols influence the rate and amount of liquid water and ice produced within these storms, the accumulated surface precipitation, the strength and timing of the updrafts and downdrafts, the longevity of the updrafts, and the strength and influence of the cold pool. Complex, nonlinear relationships and feedbacks between the microphysics and storm dynamics exist, making it difficult to make definitive statements about the effects of urbanenhanced aerosols on downwind precipitation and convection. Because the impacts of urban aerosol on downwind storms decrease with increasing background aerosol concentrations, generalization of these results depends on the unique character of background aerosol for each urban area. For urban centers in coastal areas where background aerosol concentrations may be very low, it is speculated that urban aerosol can have very large influences on convective storm dynamics, microphysics, and precipitation.

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Section: Case Studymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Urban Aerosol Impacts on Downwind Convective Storms

Heever

Cotton

2007

Journal of Applied Meteorology and Climatology

289

140

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“…또한 St. Louis를 대상으로 1971-75년 동안 수행된 Metropolitan Meteorological Experiment (METROMEX) project에 서도 강수 증가 구역이 도시와 50-75 km 풍하측에서 나타났으며, 증가량은 5-25%로 추정되었다 (Huff and Vogel, 1978;Changnon, 1979;Changnon et al, 1981;Braham et al, 1981;Changnon et al, 1991). 이러한 강수 증가는 전반적인 강수 빈도의 증가 보 다는 호우 빈도 증가와 동반되어 나타나는 경향이 있다 (Huff and Changnon, 1973).…”

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Effect of Urbanization on Rainfall Events during the 2010 Summer Intensive Observation Period over Seoul Metropolitan Area

Kim¹,

Kim²,

Kim³

et al. 2012

Journal of the Korean earth science society

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Abstract:The intensive observation (ProbeX-2010) was performed to investigate an urban effect on summer rainfall over the Seoul metropolitan area from 13 August to 3 September 2010. Two kinds of urban effect were detected. First, weak rainfall (≤1 mm hr ) was observed more frequently in the downwind area of Seoul than any other area of the country. The high frequency of weak rainfall in the downwind area was also confirmed from the recent five years of observational data (2006)(2007)(2008)(2009)(2010). Because the high frequency was more apparent in mountainous regions during nighttime, the weak rainfall seems to be caused by a combined effect of urbanization and topography. Second, sporadically, a convective system was developed rapidly in the downwind area of Seoul, causing heavy rainfall (≥10 mm hr −1). It can be most clearly seen in series of radar images around 1300-1500 KST 27 August 2010. We investigated in detail the synoptic and local weather and upper air conditions. As a result, not only urban-induced high sensible heat but also conditionally unstable atmosphere (especially unstable in low level) and low level moisture were pointed out as important factors that contributed to urban-induced heavy rainfall.

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Impacts of urbanization on Indian summer monsoon rainfall extremes

et al. 2015

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Urban areas have different climatology with respect to their rural surroundings. Though urbanization is a worldwide phenomenon, it is especially prevalent in India, where urban areas have experienced an unprecedented rate of growth over the last 30 years. Here we take up an observational study to understand the influence of urbanization on the characteristics of precipitation (specifically extremes) in India. We identify 42 urban regions and compare their extreme rainfall characteristics with those of surrounding rural areas. We observe that, on an overall scale, the urban signatures on extreme rainfall are not prominently and consistently visible, but they are spatially nonuniform. Zonal analysis reveals significant impacts of urbanization on extreme rainfall in central and western regions of India. An additional examination, to understand the influences of urbanization on heavy rainfall climatology, is carried with station level data using a statistical method, quantile regression. This is performed for the most populated city of India, Mumbai, in pair with a nearby nonurban area, Alibaug; both having similar geographic location. The derived extreme rainfall regression quantiles reveal the sensitivity of extreme rainfall events to the increased urbanization. Overall the study identifies the climatological zones in India, where increased urbanization affects regional rainfall pattern and extremes, with a detailed case study of Mumbai. This also calls attention to the need of further experimental investigation, for the identification of the key climatological processes, in different regions of India, affected by increased urbanization.

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Summary of Urban Effects on Clouds and Rain

Cited by 29 publications

References 7 publications

Urban Aerosol Impacts on Downwind Convective Storms

Urban Aerosol Impacts on Downwind Convective Storms

Effect of Urbanization on Rainfall Events during the 2010 Summer Intensive Observation Period over Seoul Metropolitan Area

Impacts of urbanization on Indian summer monsoon rainfall extremes

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